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Echo Sounding
Echo sounding is a technique where a sound beam is used to measure the depth of the sea. It can also measure the distance from the source to the nearest solid surface. The time is measured between where the sound originates and where the echo lands. The distance is evaluated by the speed of sound and the medium for which it is sent. Echo sounding is similar to radar (The Penguin Dictionary of Physics, 2009)
Echo sounding is a type of Sonar. It is mostly used to determine depth of water. The information obtained, is used to chart waters for boat passage. This is important so that ships do not run aground passing areas of underwater shelves. Echo sounding can also refer to hydro acoustics. This is active sound in water and is used to study fish. (Wikipedia, 2013). Most hydro acoustics uses mobile survey from boats to evaluate fish mass and distribution. Other forms of hydro acoustics use stationary objects to assess passing fish.
Most charted depth has been determined by standard sound speed. More advanced systems measure temperature, pressure and salinity. These addition factors are used to calculate the actual speed of sound. This more advanced system is used for navigational surveys by the US office of Coastal Survey (Wikepedia,2013). Different bodies of water need different frequencies. The deeper the water the lower the frequency needed.
More recently, radio echo sounding has been used in Antarctica. The purpose of this is to determine dry-wet bedrock or ice. The radio echoing can determine how many layers of ice there is. This is important when determining if there is excessive melting. It has been discovered that numerous sub glacial lake zones are entrapped in ice sheets. This proves water circulation between lakes or between the ice (Zirizzotti, et al., 2010).
As recent as this year, echo sounding is still being used. I found an article assessing vegetation in a lake in Japan. The use of the advanced system uses cameras as well as multibeam echo sounding to assess the abundance of submerged aquatic vegetation. The spatial distribution can be studied at different depth gradients (Abukawa, Yamamuro, Kikvidze, Asada, Xu, & Sugimoto, 2013). In this study, they found steep slopes and that the vegetation was not uniformly distributed as was thought.
I found this type of measurement important because it takes into account not only the ocean floor but the viscosity of the water. Sound travels differently through thicker or more viscous water. This brings in to account the specific gravity that was previously studied in our text book chapters. This type or research has been around for a long time. The basics are the same but the technology has gotten better. In the end, they are still using the same effective tools to map structure, height and coverage along the ocean or lake bottoms using sound.
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References
Abukawa, K., Yamamuro, M., Kikvidze, Z., Asada, A., Xu, C., & Sugimoto, K. (2012, July 3). Assessing the biomass and distribution of submerged aquatic vegatation using multibeam echo sounding in lake Towada, Japan []. Limnology, 14, 39-42. http://dx.doi.org/DOI 10.1007/s10201-012-0383-
Zirizzotti, A., Cafarella, L., Baskaradas, J., Tabacco, I., Urbani, S., Mangialetti, M., & Bianchi, C. (2010, May). Dry-Wet Bedrock Interface Detection by Radio Echo Sounding Measurements. IEEE Transactions on Geoscience and Remote Sensing, 48(5), 2343-2346. http://dx.doi.org/10.1109/TGRS.2009.2038900
Echo Sounding
Echo sounding is a technique where a sound beam is used to measure the depth of the sea. It can also measure the distance from the source to the nearest solid surface. The time is measured between where the sound originates and where the echo lands. The distance is evaluated by the speed of sound and the medium for which it is sent. Echo sounding is similar to radar (The Penguin Dictionary of Physics, 2009)
Echo sounding is a type of Sonar. It is mostly used to determine depth of water. The information obtained, is used to chart waters for boat passage. This is important so that ships do not run aground passing areas of underwater shelves. Echo sounding can also refer to hydro acoustics. This is active sound in water and is used to study fish. (Wikipedia, 2013). Most hydro acoustics uses mobile survey from boats to evaluate fish mass and distribution. Other forms of hydro acoustics use stationary objects to assess passing fish.
Most charted depth has been determined by standard sound speed. More advanced systems measure temperature, pressure and salinity. These addition factors are used to calculate the actual speed of sound. This more advanced system is used for navigational surveys by the US office of Coastal Survey (Wikepedia,2013). Different bodies of water need different frequencies. The deeper the water the lower the frequency needed.
More recently, radio echo sounding has been used in Antarctica. The purpose of this is to determine dry-wet bedrock or ice. The radio echoing can determine how many layers of ice there is. This is important when determining if there is excessive melting. It has been discovered that numerous sub glacial lake zones are entrapped in ice sheets. This proves water circulation between lakes or between the ice (Zirizzotti, et al., 2010).
As recent as this year, echo sounding is still being used. I found an article assessing vegetation in a lake in Japan. The use of the advanced system uses cameras as well as multibeam echo sounding to assess the abundance of submerged aquatic vegetation. The spatial distribution can be studied at different depth gradients (Abukawa, Yamamuro, Kikvidze, Asada, Xu, & Sugimoto, 2013). In this study, they found steep slopes and that the vegetation was not uniformly distributed as was thought.
I found this type of measurement important because it takes into account not only the ocean floor but the viscosity of the water. Sound travels differently through thicker or more viscous water. This brings in to account the specific gravity that was previously studied in our text book chapters. This type or research has been around for a long time. The basics are the same but the technology has gotten better. In the end, they are still using the same effective tools to map structure, height and coverage along the ocean or lake bottoms using sound.
-
References
Abukawa, K., Yamamuro, M., Kikvidze, Z., Asada, A., Xu, C., & Sugimoto, K. (2012, July 3). Assessing the biomass and distribution of submerged aquatic vegatation using multibeam echo sounding in lake Towada, Japan []. Limnology, 14, 39-42. http://dx.doi.org/DOI 10.1007/s10201-012-0383-
Penquin Dictionary of Physics. Retreived from http://www.credoreference.com/entry/pendphys/echo_sounding
Zirizzotti, A., Cafarella, L., Baskaradas, J., Tabacco, I., Urbani, S., Mangialetti, M., & Bianchi, C. (2010, May). Dry-Wet Bedrock Interface Detection by Radio Echo Sounding Measurements. IEEE Transactions on Geoscience and Remote Sensing, 48(5), 2343-2346. http://dx.doi.org/10.1109/TGRS.2009.2038900
Bernadette Mooney